1. Field of the Invention
The present invention relates to an improvement in a ventilation device having a heat exchanger.
2. Description of the Prior Art
There has been no ventilation device which includes a display means such as a thermometer for showing to a user temperatures of a fresh environmental air which is fed into a room after heat-exchange and of a room air to be discharged outside.
It is, therefore, necessary to show data such as an efficiency for heat exchange of room temperature to outdoor temperature on a material such as catalogue or technical information whereby effect of the heat exchange is informed to a user, thus the user relies on the ventilation device. It is especially desirable for a user to be able to observe himself a temperature difference in use of the ventilation device.